10 H. L. WIEMAN 



A seeoiul icst stage or interkinesis follows. In the prophases 

 of the second spermatocyte all of the chi'oniosomes appear bis- 

 cuit-shaped. Of 25 plates examined 24 chromosomes were 

 foimd 15 times, and 23 chromosomes 10 times. All of the chro- 

 mosomes divide in this division giving therefore two kinds of 

 spermatids; one half the total number containing 23 and the 

 other half 24 chromosomes. 



Von Winiwarter further found in the ovary of a four month 

 foetus three cases of dividing cells in which 48 chromosomes 

 could be counted, thus partially at least realizing the expectation 

 indicated by his study of the testis. 



L'espece hiimaine male coniporte 47 chromosomes somatique, I'es- 

 pece femelle 48. La fecondation d'un oeiif, contenant 24 chromosomes, 

 par un spennatozoide a 24 chromosomes aboutit au chiffre 48 c'est- 

 a-dire a line femelle, la fecondation par un spennatozoide a 23 chromo- 

 somes ail chiffre 47, a un male (p. 145). 



It will be readily understood from the foregoing that while 

 my findings incline more toward agreement with those of Guyer 

 and IVIontgomery than those of von Winiwarter, there are a num- 

 ber of points of difference. 



In the first place I believe that the spermatogonia contain 

 24 chromosomes rather than 22. The determination of the 

 munber based on counts ot spermatogonial plates alone is not 

 a simple matter in such difficult material and a difference of 2 

 in 24 is not a great deal. As a matter of fact I have never 

 counted less than 24 in material and in a few cases 25 and 26. 

 However, the evidence from the study of the growth period 

 and spermatocyte division figures taken in conjunction with 

 the facts of spermatogenesis in other animals leaves no doubt 

 in my mind that the bivalent number in the material studied 

 by me is 24 rather than 22 or 47. 



In the rest stage there is a well defined chromatin body con- 

 sisting of two unequal parts occasionally separated. Mont- 

 gomery (in figs. 2, 3, 4, 5, 6 of his paperj, pictures this body some- 

 times with the constituents united and sometimes separated. 

 I have seen both conditions in my material, but more often 

 with the parts united. Guj^er's figures are indecisive on this 



